Good news. Had plenty of sun today, so I actually had an opportunity to play with the tuner & focus a lot, and I discovered that my tuning was just way off the last time, I was able to find the sweet spot and it seems pretty evenly illuminated to me now. I also tried doing a timelapse of the sun...

Maybe it is vignetting with the B600 and the barlow on the big chip? Do you have a full disk at native focal length without the barlow? Yeah, here's an unsharpened shot of my very first image taken with the Lunt 50mm without any barlow. SunHalpha_132333_g3_ap131.jpg EDIT: And here it is cropped &am...

Tuning the etalon should move the bright area from one side to the other. You have to chose the best position. It helps to not have slop on the blocking filter too. Is the etalon square onto the scope axis? Or if it is pressure tuned is it sealing properly. Well lubricated o-ring and screw tight in...

I use the Lunt 50mm together with the ZWO ASI174MM. I tend to use a 2x barlow for more image scale. I'm having a hard time evenly illuminating the disc, sometimes it goes better than other times, like without a barlow it seemed to work fairly well, but then my last session it was very bad (see attac...